Six clinical Escherichia coli O157:H7 isolates were epidemiologically linked as part of an outbreak in which the most likely source was undercooked ground beef or cross-contamination from the ground beef to other food products at a Mexican-style restaurant. These cultures were analyzed using molecular genetic, immunological and cytotoxicity procedures. All six isolates were confirmed as E. coli O157:H7 and were indistinguishable by pulsed-field gel electrophoresis using XbaI. The results of polymerase chain reaction (PCR) tests, non-isotopic gene probing, reversed passive latex agglutination (RPLA) kit results and Vero cell assays were consistent for the presence of a functional Shiga-like toxin 1 (Stx 1) protein. All six strains produced a stx2 PCR amplicon product; five strains produced a product which was consistent with the predicted amplicon size and one (SEA 6414) produced a much larger PCR product. The SEA 6414 isolate produced a protein reactive with the RPLA kit anti-Stx 2 antibody but was not cytotoxic to Vero cells. Sequencing of this region revealed that this 1310 bp insertion was very similar to a previously identified IS 1203 sequence and the insertion interrupted the carboxyl end of the coding region of the stx2 gene 'A' subunit. Copyright (C) 2000.
All Science Journal Classification (ASJC) codes
- Food Science